This traditional pen & paper RPG level up mechanism is so screwed up for stories. It should remain with simple games and stay there. Even better computer games these days use something else. This arc demonstrated the worst aspect of it: Two strong guys beat relatively high level monsters onto the brink of death, and then some noob delivers the finishing blow of a few HP of damage with her eyes closed... and she is treated as if she did all the work and gains massive benefits, levelling up like a rocket. But perhaps this scheme somehow suits the Japanese mindset so well that they use it even when it looks, objectively, utterly stupid.